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비계공사 안전기준 개정에 따른 현장적용 실태에 관한 연구
김자연,조윤희,Kim, Ja Yeon,Cho, Youn Hee 한국안전학회 2020 한국안전학회지 Vol.35 No.4
Scaffolding works are demolished after this structure is completed, and safety accidents often occur because they are installed differently from legal standards or frequently change during work. Therefore, in order to strengthen the safety of scaffolding, the Ministry of Land, Infrastructure and Transport required a need for design standards for temporary facilities that can systematically prevent and solve large-scale safety accidents that are repeatedly increasing during temporary construction. It has been enacted, and some contents have been revised for the past three years. However, construction site personnel do not know or know the revised matters, but often install scaffolding by the installer's experience rather than complying with relevant laws and regulations. It is the situation that the ground strength test of the foundation ground for the load applied to the floor of the column is omitted in most sites. Therefore, this study grasped the actual situation on the degree of recognition of the revised laws and regulations of the construction site and the foundation-based treatment of the floor working load of the scaffolding column, and derived problems. In addition, we intend to provide reference materials for the endurance test according to the ground conditions to small-scale small sites where it is difficult to conduct the test by carrying out the endurance test of the scaffolding ground according to the revised standards.
저심도 철도 시스템에서의 열차 및 차량의 이동하중에 의한 동적거동에 관한 연구
김자연,사공명,조국환,Kim. Ja-Yeon,Sagong. Myung,Cho. Kook-Hwan 한국방재학회 2013 한국방재학회논문집 Vol.13 No.4
최근 저심도 경량전철 시스템 사업이 대두됨에 따라, 열차 및 차량 이동하중에 따른 동적거동에 관한 연구의 필요성이 대두되고 있다. 본 연구에서는 유한요소 프로그램인 LUSAS 을 이용하여 열차와 차량이 운행하고 있을 때 지표면에서의 진동 가속도값을 산정하였다. 이 수치를 사용하여 건물에 대한 진동 사용성을 평가하였다. 차량과 열차의 이동하중으로 발생하는 진동 가속도는 1 m 심도일 때 0.0042 g, 3 m 심도일 때 0.0037 g, 5 m 심도일 때 0.00048 g로써 건물의 최소 기준치인 0.102 g에 비해 매우 작은 것으로 나타났다. 이에 심도에 따른 열차주행 진동영향은 매우 적은 것으로 사료된다. As a low depth light rail system is getting issued recently, It is important to understand dynamic effects from train and car moving loads. In this study, Numerical analyses were performed to evaluate ground surface vibrations from train and car operations on low depth track system using LUSAS which is finite-element analysis program. The dynamic serviceability of a building is evaluated using analysis results. The evaluated vibratory acceleration under the moving loads of car and train at the depth of 1.0 m is 0.0042 g, 3.0 m is 0.0037 g and the value of 0.00048 g at the depth of 5.0 m. The research results show that low depth train system can be used with low vibration effect by comparing with the maximum allowable criteria of 0.102 g.
열차운행에 따른 궤도동적거동 모니터링을 위한 광섬유센서 적용성 시험
김자연 ( Kim Ja-yeon ),엄기영 ( Eum Gi-young ),박대근 ( Park Dae-geun ),임유진 ( Lim Yu-jin ) 한국구조물진단유지관리공학회 2023 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.27 No.1
현장계측은 주로 기존의 전기식 센서에 의한 계측이 이루어지고 있으나, 동시다발적인(multiplexii世) 계측이 어렵고 노이즈에 의한 정확한 측정이 이루어지지 않는다는 단점이 있다. 근래에는 상기의 문제점을 극복하기 위해서 광센서를 사용하여 계측하는 방법들이 개발되고 있으며 전기식 센서의 단점을 보완하는 센서로서 각광받고 있다. 그러나 계측의 대부분을 외국 기술 및 제품수입에 의존하고 있는 실정이며 가격이 높고 수요자에게 낯설다는 단점이 있다. 그리하여 본 연구로 센서별 동일 조건에서의 데이터 값을 직접 비교분석해 적용성 및 신뢰성을 검토하고자 한다.
김자연 ( Ja-yeon Kim ),조유현 ( Yu-hyun Cho ),박현선 ( Hyun-sun Park ),김두형 ( Doo-hyung Kim ),김민우 ( Min-woo Kim ),박종락 ( Jong-rak Park ),권민기 ( Min-ki Kwon ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.2
GaN based LEDs have gradually replaced traditional light sources in various applications including backlight display units, traffic signals, automotive lighting, architectural lighting, and general lighting. However, improvements to the external quantum efficiency (EQE) are required for these various application. The EQE of LED is correlated to the internal quantum efficiency (IQE) and the light extraction efficiency (LEE). Although the IQE of GaN-based LEDs has reached more than 80% due to the rapid development of growth techniques for high-quality epi-layers, the LEE of the LEDs is still low because of the large refractive index difference between the GaN (nGaN=2.5) and air (nair=1). Herein, various polygon shaped(triangle, parallelogram, pentagon, hexagon, circle shaped) LEDs are compared with those of a traditional quadrangular LED to enhance LEE of LED. To estimate the enhancement of LEE, we simulated the various shaped LEDs with ray-trace simulation tools. In addition, to measure the total amount of photons emitted from LEDs in all directions, the various polygon LEDs were encapsulated and packaged with To-can. Their optical output power of polygonal shaped LED is significantly improved, compared to that of traditional quadrangular LED due to increase in LEE along to lateral direction.